Image processing method

ABSTRACT

The main CPU executes Fourier transform to the partial image, then performs strict spectrum analysis  1  for judging the presence/absence of data at a coordinate position designated in advance on a Fourier transform plane with high resolution for judging the presence/absence of prohibition of duplication, then judges whether duplication-prohibited data exists or not, and clears both the partial image and the document image if it is judged that duplication-prohibited data exists. If it is judged that duplication-prohibited data does not exist, the main CPU executes spectrum analysis  2  for broadly inspecting the existence of a periodic component instead of lowering the resolution from the spectrum analysis  1  and judges whether a structure other than DC component exists or not. If the existence of a minute quantity of change that could not exist in a normal image is recognized, the main CPU performs partial image processing such as amplifying the quantity of change, then superimposes it onto the document image, and supplies the image on which the superimposing processing has been executed, to an output unit and a liquid crystal display unit, thus outputting or displaying the image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Division of application Ser. No. 11/474,185 filedJun. 23, 2006, the entire contents of which are hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an image processing method for an imageprocessing apparatus that reads an image of a manuscript and processesthe read image of the manuscript.

2. Description of the Related Art

A technique of embedding a watermark or the like in advance into adocument image the duplication of which is not permitted, and thusprohibiting the duplication of the image itself, or a technique ofembedding data related to the contents of a document and thus preventingfalsification of the data and the contents of the document of thecorresponding part, is becoming generally popularized.

However, though a method of embedding information of copyright owner andprohibition of duplication into a part that constitutes an entire targetimage for copyright protection and thus limiting changes and downloadingof a file is employed mainly with respect to soft copies in networkdistribution, for an image that is very likely to be misused afterduplication such as a stamp or sign that is additionally written aftermaking a hard copy, it is difficult to embed data indicating prohibitionof duplication into the image in advance.

As described above, stamps and signatures vary in shape and size, anddetection of them is difficult by using a method like pattern matching.Also, unless a target image is changed to a predetermined color inprinting from a monochrome read image, or unless an image is recordedafter its original image is magnified at an extremely large or smallmagnification, an image equivalent to the target image can be acquiredby magnifying again to the size of the original image. Therefore,compared with other specific images, duplication and use of them can beeasily carried out. Thus, there is a problem that the possibility ofmisuse is high.

BRIEF SUMMARY OF THE INVENTION

The object of an aspect of the present invention is to provide an imageprocessing method for an image processing apparatus that enablesdetection of an image of a stamp, sign or the like, in which informationcannot be embedded because its detection is difficult and it is oftenadditionally written later, and thus enables prevention of misuse afterslicing and duplication.

According to an aspect of the present invention, there is provided animage processing method for an image processing apparatus configured toperform predetermined processing to document image data and supply theprocessed document image data to an output unit or a storage unit,comprising the step of: performing embedding processing of dataexpressed by a minute change in value of a pixel with respect to apreset area, when expanding the document image data to bit map data.

Additional objects and advantages of an aspect of the invention will beset forth in the description which follows, and in part will be obviousfrom the description, or may be learned by practice of the invention.The objects and advantages of an aspect of the invention may be realizedand obtained by means of the instrumentalities and combinationsparticularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate preferred embodiments of theinvention, and together with the general description given above and thedetailed description of the embodiments given below, serve to explainthe principles of an aspect of the invention.

FIG. 1 is a block diagram showing a schematic configuration of amultifunction peripheral having an image processing apparatus of thisinvention;

FIG. 2 is a view for explaining an embedding operation in an imageprocessing method according to a first embodiment;

FIG. 3 is a view for explaining the details of embedding to an image;

FIG. 4 is a view for explaining an operation at the time of reading inthe image processing method;

FIG. 5 is a view showing a spectral arrangement on a Fourier transformplane;

FIG. 6 is a view for explaining image superimposing processing accordingto the first embodiment;

FIG. 7 is a flowchart for explaining operations of the imagesuperimposing processing;

FIG. 8 is a view for explaining image superimposing processing accordingto a second embodiment; and

FIG. 9 is a view for explaining image superimposing processing accordingto a third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of this invention will be described withreference to the drawings.

FIG. 1 shows a schematic configuration of a multi function peripheral(hereinafter described as MFP) 10 having an image processing apparatusof this invention.

As shown in FIG. 1, the MFP 10 includes a main CPU 1, a ROM 2, a RAM 3,an input unit 4, an image processing apparatus 5, a storage unit 6, anoutput unit 7, and an operating panel 8. The foregoing constituentelements are connected via a bus 20 with the main CPU 1 situated at thecenter.

The main CPU 1 is in charge of the overall operations of the MFP 10 andoperates in accordance with programs stored in advance in the ROM 2.

The RAM 3 stores image data or various types of information.

The input unit 4 optically scans a manuscript and changes the manuscriptto image data.

The image processing apparatus 5 has a pattern recognizing unit 11 and agray level correcting unit 12, and performing various types ofprocessing to image data. The pattern recognizing unit 11 performspattern recognition for judging duplication-prohibited image data or thelike. The gray level correcting unit 12 corrects the gray level of imagedata.

The storage unit 6 is formed by a hard disk device or the like andstores image data or various types of information.

The output unit 7 prints image data or the like onto a paper.

The operating panel 8 has a display that is formed by a liquid crystaldisplay unit 9 with a built-in touch panel, and plural hard keys. Inthis operating panel 8, various operations in the MFP 10 are carried outby using the plural hard keys and the liquid crystal display unit 9 withthe built-in touch panel.

Next, the outline of this invention in such a configuration will bedescribed.

FIG. 2 illustrates embedding in the image processing method according tothe first embodiment.

As shown in FIG. 2, first, a document file (template file) formed bycomplementing a template or text of a document image having aduplication-prohibited part by using document processing software isinputted from the input unit 4 (a). Next, a duplication-prohibited area(indicated by a dotted line in FIG. 2) of the template file or documentfile is designated in advance, and a minute change that can be hardlyvisually recognized is made in the area, thus embedding informationindicating prohibition of duplication from the image processingapparatus 5 (b). The document image to which the embedding processinghas been done is outputted as a hard copy via the storage unit 6 and theoutput unit 7, and a sign or stamp is additionally written in thecorresponding part where the data indicating prohibition of duplicationhas been embedded (c, d).

FIG. 3 shows an exemplary pattern in the case where this data indicatingprohibition of duplication is embedded as a periodic component. If thevoltage of embedded data is plural bits, data modulation of plural typesof periodic components having difference periods and angles as shown inFIG. 3 is superimposed on a signal value of the original image, and asignal value d after superimposing the data on the original signal valued0 is acquired by the following equation.

$d = {{d\; 0} + {\sum\limits_{n = 1}^{b\; n}{{WAn}*{\cos \left( {{{\cos \left( {W\; \theta \; n} \right)} \times 2i\; {\pi/{WLn}}} + {{\sin \left( {W\; \theta \; n} \right)} \times 2j\; {\pi/{WLn}}}} \right)}}}}$

Here, bn represents the number of bits of data to be superimposed. WAnrepresents the amplitude of the periodic component. Wθn represents theangle formed with the main scanning direction of the period component.WLn represents the period, and i, j represent a position of a targetpoint in the main scanning direction and sub scanning direction.

In this manner, additional writing can be carried out by making a changerepresenting information of prohibition of duplication or the like in atarget area in advance, and even an image in which a target partialimage has largely varied color and shape so that detection of this imagepart is difficult, can be a subject for prohibition of duplication.

Regardless of whether duplication is permitted or not, the additionaldata may include the date of creation, distribution range, degree ofconfidentiality and the like.

FIG. 4 shows an operation at the time of reading. An image formed bysuperimposing a sign or stamp to be a subject for prohibition ofduplication onto an area where data has been embedded, is read by theinput unit 4 (e), and the target image is taken in as a data file (f).Also a scanner, copy machine or digital camera may be used.

In the case of trying to slice out and save the target part where thedata of prohibition of duplication has been embedded, of the image takenin as a data file, if the image processing apparatus 5 that executes theslicing of the image can detect the data embedded in this image area,the main CPU 1 compares the extracted data with the data stored in thestorage unit 6 that is directly connected with the judgment, andexecutes judgment on whether the data, is a subject for prohibition ofduplication or the like.

In the case where the technique of superimposing plural periodiccomponents as described above is employed for embedding here, whenFourier transform is executed, peaks in spectral value of angle andfrequency of the embedded periodic components can be confirmed on afrequency surface, as shown in FIG. 5. This spectral value of the targetangle and frequency is compared with a predetermined threshold value andthen on/off of the bit is judged, thus detecting the embedded data. Ifthe target part is judged to be duplication-prohibited in the stagewhere this data is detected, the setting is made so that execution ofslicing or additional saving of the sliced part will be stopped. Also, awarning may be issued that indicates prohibition of duplication.

If the image processing apparatus 5 cannot be detect the data, as in thecase where it cannot confirm the existence of the data by comparing withthe periodic component stored in the storage unit 6 in advance otherthan the original image, the input image is saved at least withoutcausing degradation of the partial image of the input image (g), andduplication can be prevented when the sliced partial image is reused(h).

FIG. 6 shows a process related to overlay processing in the case wherethe slicing or saving of a target part of an image according to thefirst embodiment is executed in another image processing system and thenprovided. When (k) superimposing a sliced partial image (i) on anotherdocument file (j), if information of prohibition of duplication isrecognized in the partial image, the superimposed image itself isstopped (l). If data of prohibition of duplication is not recognized butthe existence of a minute quantity of change which could not exist in anormal image is recognized, the minute change is emphasized and thensuperimposed on a document image that is an overlay target (m).

Next, the above-described image processing according to the firstembodiment will be described with reference to the flowchart of FIG. 7.

The main CPU 1 first executes Fourier transform to the partial image(ST1), then performs strict spectrum analysis 1 for judging thepresence/absence of data at a coordinate position designated in advanceon a Fourier transform plane with high resolution for judging thepresence/absence of prohibition of duplication (ST2), and judges whetherduplication-prohibited data exists or not (ST3). If it is judged thatduplication-prohibited data exists, the main CPU 1 clears both thepartial image and the document image (ST4).

If it is judged in step ST3 that duplication-prohibited data does notexist, the main CPU 1 executes spectrum analysis 2 for broadlyinspecting the existence of a periodic component instead of lowering theresolution from the spectrum analysis 1 (ST4) and judges whether astructure other than DC component exists or not (ST5).

If the existence of a minute quantity of change that could not exist ina normal image is recognized, the main CPU 1 performs partial imageprocessing such as amplifying the quantity of change and thensuperimposes it onto the document image (ST6, 7). The main CPU 1supplies the image on which the superimposing processing has beenexecuted, to the output unit 7 and the liquid crystal display unit 9,thus outputting or displaying the image (ST8).

As described above, according to the first embodiment, in the case wherethere is an image that is very likely to be misued as it is sliced out,duplicated and superimposed on another document image, the misuse can beprevented by performing the above-described processing.

Next, a second embodiment will be described.

In the above-described first embodiment, if the existence of dataindicating prohibition of duplication is recognized, the processing iscarried out so as not to perform output or display itself, whereas themain CPU 1 in this second embodiment changes the partial image into anon-reusable shape by doubly superimposing the partial image (n) asshown in FIG. 8, or otherwise, and thus performs control to preventmisuse of the image.

Next, a third embodiment will be described.

The main CPU 1 in the third embodiment makes a change such as erasing apart of color channels from the partial image (s) or arranging thepartial image in one channel of monochrome alone (r) as shown in FIG. 9,and thus performs control to prevent misuse of the image.

As described above, according to the embodiments of the invention, withthe above-described configuration, data indicating prohibition ofduplication is embedded in advance into a part where a predeterminedimage is additionally written, in a document image, thereby enablingsuperimposition of information even for target images having variousshapes and sizes. Also, even for an image that has largely varied shapeand size and that cannot be dealt with by an ordinary detecting method,slicing processing can be prevented. Even for an image that has beensliced out because it was not found in the detection, the image isdetected when it is superimposed on another document, and a change ismade in the sliced image or its output or display is stopped, therebyenabling prevention of misuse.

Moreover, even when it cannot be judged that the image isduplication-prohibited because the system that embedded the informationis different, a minute change that is different from a normal documentimage is detected and the change is emphasized, thereby enablingprevention of misuse of the sliced image.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. An image processing method for an image processing apparatusconfigured to perform predetermined processing to document image dataand supply the processed document image data to an output unit or astorage unit, comprising: judging the existence of at least one embeddeddata when performing processing to superimpose partial image data slicedout from a predetermined document data and the document image data, andif the existence of data indicating prohibition of duplication of thepartial image data sliced out from the predetermined document data isrecognized by this judgment, issuing a warning to the effect that thesuperimposition of the partial image data sliced out from thepredetermined document data is prohibited, thus stopping thesuperimposing processing.
 2. An image processing method for an imageprocessing apparatus configured to perform predetermined processing todocument image data and supply the processed document image data to anoutput unit or a storage unit, comprising: judging the existence of atleast one embedded data when performing processing to superimposepartial image data sliced out from a predetermined document data and thedocument image data, and if the existence of data indicating prohibitionof duplication of the partial image data sliced out from thepredetermined document data is recognized by this judgment, performingprocessing to change the partial image data sliced out from thepredetermined document data to an image density different from itsoriginal image and then superimpose the image.
 3. An image processingmethod for an image processing apparatus configured to performpredetermined processing to document image data and supply the processeddocument image data to an output unit or a storage unit, comprising:judging the existence of at least one embedded data when performingprocessing to superimpose partial image data sliced out from apredetermined document data and the document image data, and if theexistence of data indicating prohibition of duplication of the partialimage data sliced out from the predetermined document data is recognizedby this judgment, performing processing to reproduce in achromatic colora part that should be reproduced in chromatic color, of the partialimage data sliced out from the predetermined document data.
 4. An imageprocessing method for an image processing apparatus configured toperform predetermined processing to document image data and supply theprocessed document image data to an output unit or a storage unit,comprising: judging the existence of at least one embedded data whenperforming processing to superimpose partial image data sliced out froma predetermined document data and the document image data, and if theexistence of data indicating prohibition of duplication of the partialimage data sliced out from the predetermined document data is recognizedby this judgment, performing processing to shift the partial image datasliced out from the predetermined document data to double positions andthen superimpose the image.